JPH1135957A - Gas refining and gas refining facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more practical gas refining method wherein a sulfur compd. is removed from the gas produced at a coal gasification process or the like, and after a regenerated gas contg. a sulfur compd. is converted by burning to a flue gas contg. sulfur dioxide, it is recovered as gypsum, while economic problems regarding the burning process is eliminated. SOLUTION: For a combustion room 121 for burning a sulfur compd. more than one heat storage bodies 122 are built and combustion is done heating the regenerated gas E2 by recovered heat of the flue gas E3 using the heat storage bodies as media by continuing an operation comprising contacting a specific one of these heat storage bodies with a flue gas E3 after burning to heat the body and, at the same time, contacting other heat storage bodies with a regenerated gas E2 before burning to heat the regenerated gas by switching the heat storage body by turns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas purification method for removing a sulfur compound from a product gas of a coal gasification process or the like, converting the sulfur compound into a sulfurous acid gas, and recovering the sulfur compound as gypsum. The present invention relates to a gas purification method in which a combustion step of converting a sulfur compound into sulfur dioxide is realized at low cost and practically.

[0002]

2. Description of the Related Art In recent years, fuel resources have been depleted and soaring prices have led to a demand for diversification of fuels. Coal and heavy oil utilization technologies have been developed. One of them is coal and heavy oil. The technology of gasifying methane into a power generation fuel or a synthetic raw material has attracted attention. In addition, power generation using gasified gas is more efficient than conventional thermal power generation using coal or oil, and thus has attracted attention in terms of effective use of limited resources.

However, this gasification product gas contains several tens of
It contains 0 to several 1000 ppm of sulfur compounds (mainly hydrogen sulfide), which must be removed to prevent pollution or to prevent corrosion of downstream equipment (for example, gas turbines). Thus, as shown in, for example, JP-A-6-293888 and JP-A-7-48584, a gas is brought into gas-liquid contact with a sulfur compound absorbing solution to remove the sulfur compound in the gas and to remove the sulfur compound. There is known a wet gas purification method in which heat is applied to an absorbed absorbent to discharge a regeneration gas containing a sulfur compound, and the absorbent is sequentially regenerated and reused.

[0004] As a method of treating sulfur compounds in the regenerated gas generated by such a gas purification method, as described in the above-mentioned publication, the regenerated gas is burned and converted into flue gas containing sulfurous acid gas. There is a method in which sulfur dioxide gas in the smoke is absorbed by a wet lime gypsum method to produce gypsum as a by-product.

[0005]

According to the above-mentioned conventional gas purification method, there is an advantage that it is possible to clean more and a useful gypsum can be obtained as compared with a dry gas purification method. However, the inventors have found that there are problems to be further improved in order to more economically perform the above gas purification method.

(1) If a general combustion furnace is used as the means for burning the regenerated gas, auxiliary fuel is required, which not only increases the fuel cost, but also increases the amount of smoke exhausted. The device capacity becomes extremely large, and the operating cost also increases.

[0007] That is, the concentration of hydrogen sulfide in the regeneration gas varies depending on the type of gasification raw material and the like, but is, for example, about 20 vol%. In a general combustion furnace, auxiliary fuel must be continuously supplied. If combustion does not continue stably.
For this reason, in addition to the regeneration gas and air for burning the hydrogen sulfide contained therein, auxiliary combustion fuel and air for burning the combustion gas must be introduced into the combustion furnace, and the flue gas generated in the combustion process must be supplied. Flow rate is constantly enormous. When the flow rate of the flue gas increases, all the equipment such as the ducts constituting the flue gas flow path after the combustion process and the absorption tower for absorbing the sulfurous acid gas becomes large, and fans and blowers for supplying the gas and the like are used. Operating costs also increase.

(2) When the regenerated gas is burned at a low temperature, the concentration of SO _{3 in} the flue gas becomes high, and special measures such as improving the corrosion resistance of the equipment after the combustion step are required. This leads to an increase in equipment costs. That is, when hydrogen sulfide is burned, mainly S is produced by the reaction shown in the following reaction formula (1).
Although O ₂ (sulfurous acid gas) is generated, a SO ₃ generation reaction represented by the following reaction formula (2) also occurs.

[0009]

Embedded image H ₂ S + 3 / 2O ₂ → SO ₂ + H ₂ O (1) H ₂ S + 2O ₂ → SO ₃ + H ₂ O (2)

Here, as shown in FIG. 8 described later, the ratio of the SO ₃ generation reaction in the reaction formula (2) increases as the combustion temperature decreases, and the SO ₃ concentration in the combustion exhaust gas decreases. To increase. At low temperatures, such as normal flue gas temperature, this SO ₃ becomes a highly corrosive sulfuric acid mist, so it is necessary to use a more expensive corrosion-resistant material that can withstand the components of the duct and desulfurization tower after the combustion process. Whether to configure, or keep the entire duct etc. at high temperature to prevent sulfuric acid mist from being generated,
Alternatively, it is necessary to take special measures such as injecting a large amount of ammonia into the flue gas for neutralization. For this reason, it is important to minimize the amount of SO ₃ generated.

If the concentration of hydrogen sulfide is high, there is no auxiliary fuel and even in a general combustion furnace, for example, 600 to
Although combustion can be performed at a low temperature of about 700 ° C., in this case, the amount of SO ₃ generated is increased as described above, which is economically disadvantageous due to the above problem (2). Therefore, if an attempt is made to raise the combustion temperature, an auxiliary fuel is also required for that purpose, and the problem (1) is inferior in economical practicability.

Accordingly, the present invention relates to a gas purification method or a gas purification apparatus for removing a sulfur compound from a product gas of a coal gasification process or the like, burning the sulfur compound, converting the sulfur compound into a sulfurous acid gas, and recovering it as gypsum. It is an object of the present invention to provide a gas purification method or a gas purification apparatus which solves the above-mentioned problems relating to the combustion process and is more economically practical.

[0013]

To achieve the above object, a gas refining method according to claim 1 is a gas refining method for purifying a product gas obtained by gasifying coal or petroleum. A desulfurization step of absorbing and removing the sulfur compound contained in the product gas by gas-liquid contact with an absorption solution of the sulfur compound, and applying heat to the absorption solution that has absorbed the sulfur compound in the desulfurization step to convert the sulfur compound A regeneration process of discharging the regeneration gas containing the gas, a combustion process of burning the regeneration gas generated in the regeneration process to convert the gas into a flue gas containing a sulfur dioxide gas, and a wet lime process of the sulfur dioxide gas in the flue gas generated in the combustion process. A gypsum collecting step of absorbing gypsum to produce gypsum, providing a plurality of heat storage bodies in a combustion chamber for performing the combustion step, and discharging the heat to any one of these heat storage bodies. And heating the regeneration gas by bringing the regeneration gas before combustion into contact with another thermal storage body at the same time as heating the specific thermal storage body by contacting the thermal storage medium with the other thermal storage body. Thus, the combustion step is performed while heating the regeneration gas with heat recovered from the flue gas using the heat storage medium as a medium.

Further, in the gas refining method according to a second aspect, the combustion temperature of the regenerated gas in the combustion step is set to 1000 ° C. or higher.

[0015] The gas refining facility according to claim 3 is a gas refining facility for purifying a product gas obtained by gasifying coal or petroleum, wherein the product gas is brought into gas-liquid contact with a sulfur compound absorbing solution. A desulfurization tower that absorbs and removes a sulfur compound contained in the product gas, a regeneration tower that discharges a regeneration gas containing the sulfur compound by applying heat to the absorbent that has absorbed the sulfur compound in the desulfurization tower, A regenerative heat exchange combustion furnace that burns the regenerated gas generated in the tower to convert it to flue gas containing sulfur dioxide gas, and absorbs the sulfur dioxide gas in the flue gas generated by this regenerative heat exchange combustion furnace by the wet lime gypsum method And a desulfurization device that produces gypsum as a by-product, wherein the regenerative heat exchange combustion furnace comprises a combustion chamber, and a plurality of heat exchange flow passages each of which is connected to the combustion chamber in a parallel state and in which a heat storage body is loaded. Composed and heat exchange Road is characterized in that the sequential switching is configured as a discharge path for introducing passage or the exhaust fumes of the regeneration gas to the combustion chamber.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 to FIG. 5 are diagrams showing gas purification equipment for implementing an example of the present invention. Hereinafter, for convenience of explanation, the equipment is divided into a plurality of parts (gas cleaning unit, desulfurization regeneration unit, combustion cooling unit, gypsum collection unit, and wastewater treatment unit).
Will be described separately. FIG. 1 is a diagram showing a configuration of a gas cleaning unit, FIG. 2 is a diagram showing a configuration of a desulfurization regeneration unit, FIG. 3 is a diagram showing a configuration of a combustion cooling unit, and FIG.
FIG. 5 is a diagram illustrating a configuration of a gypsum collection unit, and FIG. 5 is a diagram illustrating a configuration of a wastewater treatment unit. Further, the gypsum recovery unit shown in FIG. 4 corresponds to the desulfurization device of the present invention.

First, the configuration and operation of the gas cleaning unit will be described with reference to FIG. In a gasification furnace not shown, for example, coal is gasified using air as a gasifying agent, and a generated gas A1 mainly containing carbon monoxide and hydrogen is generated. As described above, the generated gas A1 using coal as a raw material and air as a gasifying agent usually contains about 1000 to 1500 ppm of H.
₂ S (sulfur compound) and about 100 ppm of COS (sulfur compound) are contained.
It contains about ₃ pm of NH ₃ and about 100 ppm of HCl. Immediately after the furnace outlet, the generated gas A is usually at 1000 ° C. to 2000 ° C., but is usually recovered by a steam heater (not shown) provided at the furnace outlet side and cooled to, for example, about 350 ° C. Is, for example, about 26 ata.

The generated gas A1 is subjected to dust removal processing using a cyclone or a porous filter (not shown).
As shown in the figure, a heat exchanger 1 having a shell and tube structure
Will be introduced. In the heat exchanger 1, the purified gas A4 is heated by the heat of the generated gas A1, and the gas A1 is deprived of heat and cooled to, for example, about 230 ° C.

In the downstream of the heat exchanger 1, there are provided two converters 2 in which catalysts for converting COS (carbonyl sulfide) into H ₂ S are provided in this case, and COS in the product gas A1 is provided.
Are converted to H ₂ S here. Further, a heat exchanger 3 having a shell-and-tube structure is provided downstream of the converter 2, and the gas A4 that has been purified by the heat of the gas A2 derived from the converter 2 is heated.

The gas A2 is located downstream of the heat exchanger 3.
Is brought into gas-liquid contact with the cleaning solution B1 or B2, and HCl or N
Washing towers 4a and 4b for removing impurities such as H ₃ are sequentially provided. In this case, the washing towers 4a and 4b are so-called packed type gas-liquid contact towers, in which the washing liquid B1 or B2 mainly containing water stored in the bottom of the tower is sucked up by the circulation pump 5 and sprayed at the top of the tower. The gas A2 is injected from the pipe 6, is introduced from the lower part of the tower, and flows down through the filler 7 while being in gas-liquid contact with the gas A2, and returns to the bottom of the tower and circulates again.

Here, a part of the cleaning solution B1 or B2 is
In this case, the flow paths 5a branched from the discharge side of the circulation pump 5
5b, and is discharged as drainage B3. Further, to the bottom of the washing tower 4b on the downstream side, an amount of makeup water B4, which is discharged as waste water B3 or supplements the amount contained in the gas and carried away, is supplied as appropriate. A mist eliminator 8 for separating and removing mist in the gas, and a spray pipe 9 for injecting cleaning water B5 to the mist eliminator 8 are provided above the towers of the respective washing towers 4a and 4b.
And the amount of so-called entrained mist flowing to the downstream side is suppressed to a low level. Cleaning water B5
In this case flows down to the bottom of the tower and becomes part of the washing liquid.

Further, at the bottom of each of the washing towers 4a and 4b,
The acid (in this case, sulfuric acid) stored in the tank 10 is
The supply of the sulfuric acid is adjusted by the control means (not shown) according to the detected value of the pH of each cleaning liquid, so that the pH of each cleaning liquid is adjusted as follows, for example. Is done.

That is, the cleaning liquid B1 in the cleaning tower 4a
Is maintained at an optimal value for absorption of HCl (for example, in a weakly acidic region or a neutral region) within a range not excessively absorbing H ₂ S, and the pH of the washing solution B2 in the washing tower 4b is adjusted to
Maintain a relatively low value (eg, strongly acidic region or weakly acidic region) that is optimal for absorption of NH ₃ .

By adjusting the pH in this manner, most of the HCl is absorbed in the washing tower 4a, and NH ₃ remaining without being absorbed in the washing tower 4a can be almost completely absorbed and removed in the washing tower 4b. In addition, even when the contents of HCl and NH ₃ change separately, the pH of each washing tower is adjusted to the optimum value accordingly, and the circulation amount of the washing liquid is adjusted to the minimum necessary in each washing tower. In addition, all of these harmful substances can be almost completely absorbed and removed while the operating cost is kept to a minimum.

In this embodiment, a part of the cleaning liquid B2 discharged from the cleaning tower 4b is introduced into the cleaning tower 4a through a flow path 5c branched from the discharge side of the circulation pump 5 to reduce the total amount of drainage. We are trying to reduce it. Further, in this case, by controlling the flow rate of the flow path 5a and the flow path 5c by a control means (not shown), the liquid level of the washing tower 4a is controlled within a certain range. Is adjusted, the liquid level of the washing tower 4b is controlled within a certain range.

In this embodiment, as shown in FIG. 1, a cooler 12 for cooling each of the cleaning liquids B1 and B2 is provided in each of the cleaning towers. The cooler 12 is a heat exchanger provided on the way of the circulation path of the cleaning liquid, and cools the cleaning liquid by passing, for example, industrial water.

In this embodiment, the cooler 12
The temperature of the gas and the cleaning liquid is adjusted to a temperature preferable for absorbing impurities, and the temperature of the gas derived from the first cleaning tower 4a is reduced in the second cleaning tower 4b.
The operating temperature is controlled. In this case, the heat exchanger 3
And fume-like submicron particles made of ammonium chloride and the like precipitated by cooling the gas A2 by the washing tower 4a,
In the washing tower 4b, the water is actively collected by the condensed water.

That is, since the gas discharged from the washing tower 4a is in a state where the contained steam is saturated, the washing tower 4a
When the temperature of this gas decreases in b, condensed water is always generated and condensed with the submicron particles in the gas as nuclei. Therefore, most of the submicron particles are condensed with this condensed water in the washing tower 4b. Collected in the cleaning solution B2.

Next, the structure and operation of the desulfurization regeneration unit will be described with reference to FIG. The desulfurization section mainly includes a desulfurization tower 21 and a regeneration tower 22.
And The desulfurization tower 21 is a countercurrent gas-liquid contact tower, and the hydrogen sulfide absorbing liquid C collected at the bottom of the regeneration tower 22
1 is sucked up by the circulation pump 23, cooled by the absorption liquid heat exchanger 24 and the absorption liquid cooler 25, and then supplied into the desulfurization tower 21. The supplied absorbing liquid C1 is introduced into the bottom of the desulfurization tower 21 and comes into gas-liquid contact with the ascending gas A3, and flows down via the filler 26 while absorbing H ₂ S in the gas. Then, the absorbent C1 collected at the bottom of the desulfurization tower 21 is returned to the regeneration tower 22 via the absorbent heat exchanger 24 via the line 21a.

On the other hand, the gas A3 that rises after passing through the filler 26 further rises sequentially through the steps 27 and the filler 28 provided above the filler 26, and is supplied from the outside to the spray pipe. After gas-liquid contact with the absorbing liquid C2 (for example, industrial water) injected from 29 to further remove H ₂ S and submicron particles, the gas is passed through the mist eliminator 30 as purified gas A4 from the top of the tower. It is configured to be discharged.

Here, the absorption liquid heat exchanger 24 is connected to the regeneration tower 22 via a line 22a provided with the above-mentioned pump 23.
Has a shell-and-tube structure for performing heat exchange between the absorbent C1 supplied from the desulfurization tower 21 to the desulfurization tower 21 and the absorbent C1 returned from the desulfurization tower 21 to the regeneration tower 22 via the aforementioned line 21a. It is a heat exchanger. The absorbing liquid cooler 25 is a heat exchanger having a shell-and-tube structure for cooling the absorbing liquid C1 supplied from the regeneration tower 22 to the desulfurizing tower 21, and water C3 such as industrial water is passed as a refrigerant.

The shelf 27 of the desulfurization tower 21 is a horizontal partition wall provided above the supply position of the absorbing liquid C1 and partitioning the inside of the desulfurizing tower 21 so as to receive the absorbing liquid C2 flowing down. A plurality of so-called bubble bells (not shown) are provided, and the gas A3 rising through the bubble bells is passed through and blown out from the upper surface in the form of bubbles. The absorption liquid C2 stored on the upper surface side of the shelf 27 is sucked up by the pump 31, supplied to the spray pipe 29 and circulated. The solution is sent to the above-mentioned line 21a via 21b, and finally sent to the regeneration tower 22 as a part of the absorbing solution C1.

Also, the spray pipe 29
A cooler 32 that cools the absorbing liquid C2 with industrial water or the like is provided in the middle of the supply flow path to the cooling water. When the cooler 32 is provided in this manner, the temperature of the gas in contact with the absorbent C2 injected from the spray pipe 29 at the upper part of the desulfurization tower 21 is further cooled, and the temperature of the gas remaining in the gas remains. The submicron particles increase in diameter due to condensation of water and are collected here as well.

The purified gas A4 is heated by the heat exchanger 3 and the heat exchanger 1 shown in FIG. 1 and then supplied as a purified gas A5 to, for example, a gas turbine of a coal gasification gas power generation facility. You. The pressure of the purified gas A5 is, for example, about 25.5 ata, its temperature is about 300 ° C., and its sulfur content (the concentration of H ₂ S and COS) is 10 ppm or less.

The absorbing solution C1 containing a hydrogen sulfide absorbing agent
Is supplied from the absorbing liquid tank 34 to the aforementioned line 22a (the suction side of the aforementioned pump 23) by the pump 33. A part of the absorbing liquid C1 is sent to a neutralization tank 36 via a line 35 branched from the line 22a (the discharge side of the pump 23).
After being neutralized in this neutralization tank 36, it is returned to the regeneration tower 22 by a pump 37. A part of the absorbent C1 sent from the neutralization tank 36 by the pump 37 is heated by the steam D1 in the heater 38,
Returned to 2.

On the other hand, in the regeneration tower 22, the absorbent C1 collected at the bottom of the desulfurization tower 21 is heated by the absorbent heat exchanger 24 via the above-mentioned line 21a and then distributed to the center of the tower. The gas is supplied to the upper surface side of the provided packing material 39 and flows down through the packing material 39 while being in contact with the vapor or absorption component (off gas) of the absorbing liquid C1 rising in the column.

The absorption liquid C1 at the bottom of the regeneration tower 22 is
Heat is heated by the steam D 2 in the heater 40, whereby H ₂ S, which is an absorption component, is diffused to the gas side in the regeneration tower 22. And this H ₂ S
The off-gas E1 containing a gas passes through a mist eliminator 41 and a reflux section provided at the top of the regeneration tower 22, and as a regenerated gas E2 (main component CO ₂ ) containing H ₂ S at a higher concentration, is sent to a gypsum recovery section described later. Sent.

Here, the reflux section is generated by cooling the off-gas E1 by the cooler 42,
The condensate C4 of the off-gas E1 stored in the pump 44
Is supplied to the top of the regenerator 22 and flows down through the filler 45. As a result, the vapor in the off-gas E1 is liquefied more, while H _2, which is an absorbing component in the liquid, is liquefied.
S diffuses more, eg 20% by volume percent
A regeneration gas E2 containing H ₂ S at a high concentration is obtained.

The absorbing liquid C2 (for example, industrial water) supplied from the outside is mixed with the absorbing liquid C4 supplied to the top of the regeneration tower 22 by the pump 44. In addition, a part of the absorbing liquid C4 is mixed with the wastewater B3 from the above-mentioned washing tower via a line 46 branched from the discharge side of the pump 44, and is sent as a wastewater B4 to a combustion cooling unit described later. The cooler 42 is provided with an off-gas E by a refrigerant C5 such as industrial water.
1 is a heat exchanger having a shell and tube structure for cooling the heat exchanger 1.

Next, the configuration and operation of the combustion cooling section will be described with reference to FIG. The combustion cooling unit includes a buffer tank 51 for temporarily storing the regeneration gas E2 sent from the desulfurization regeneration unit, and the regeneration gas E2 discharged from the buffer tank 51 is supplied to the air F1, F2 or an off-gas B7 (see FIG.
And a combustion fluid 52 that burns the H ₂ S contained therein, and a flue gas E3 produced by burning the regenerated gas E2 in the combustion furnace 52 is supplied with a cooling liquid G1 composed of industrial water or the like. A cooling tower 53 to be brought into contact is provided.

Here, the combustion furnace 52 is a regenerative heat exchange combustion furnace, to which air F 1 and F 2 are supplied from blowers 54 and 55. The detailed configuration and operation of the combustion furnace 52 will be described later with reference to FIGS. In the combustion furnace 52, a slight amount of ammonia in the off-gas B7 and nitrogen in the air F1 and F2 are burned to generate nitrogen oxides. Therefore, depending on the required nitrogen oxide emission concentration, for example, dry denitration The device may be provided downstream of the combustion furnace 52.

In the combustion furnace 52, the amount of sulfur trioxide (SO ₂₎ is small due to the combustion of H ₂ S as compared with SO _2.
3 ) is also generated. If this sulfur trioxide is left as it is, it combines with the ammonia slightly remaining in the gas to form acidic ammonium sulfate (NH ₄ HSO ₄ ) which is highly corrosive and easily becomes a scale, or according to the characteristics of sulfuric acid dew point. It becomes a highly corrosive sulfuric acid mist. Further, since the sulfuric acid mist formed by condensation of sulfur trioxide is usually submicron particles, it cannot be collected by an absorption tower 61 (shown in FIG. 4) described later, and is contained in a smoke exhaust E5 described later. Released to the atmosphere.

Therefore, in addition to the amount required for the above-mentioned denitration treatment, the amount of neutralizing sulfur trioxide in the flue gas E3 into harmless ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) which is easy to collect is also considered. A large amount of ammonia may be injected into the flue gas E3. In addition,
As the ammonia, ammonia water M3 or M5 (shown in FIG. 5) collected in a wastewater treatment section described later can be used.

The cooling tower 53 is provided with a cooling liquid G1 collected at the bottom.
Is sucked up by the circulation pump 56, is injected from the top of the tower, and comes into gas-liquid contact with the flue gas E3 that is introduced into the bottom of the tower and rises. The cooled flue gas E3 is discharged from the tower top as cooled flue gas E4. A cooler 57 for cooling the circulating cooling liquid G1 with industrial water or the like is provided on the discharge side of the circulation pump 56. Also, from the top of the cooling tower 53, makeup water G2 such as industrial water is supplied as water constituting the cooling liquid G1. Further, the cooling liquid G
Part of the wastewater B4 is discharged from a line 58 branched from the discharge side of the circulation pump 56 and sent from a desulfurization regeneration unit.
And sent to the wastewater treatment section described below as wastewater B5.

Next, the configuration and operation of the gypsum collecting section (desulfurization device) will be described with reference to FIG. The gypsum recovery section of the present example mainly uses SO ₂ (sulfurous acid gas) from the flue gas E4 discharged from the combustion cooling section by a slurry-like absorbing liquid H1 containing a calcium compound J1 (hereinafter referred to as an absorbent slurry H1). ) To remove gypsum and produce gypsum as a by-product.

In this desulfurization apparatus, the flue gas E4 containing a high concentration of sulfurous acid gas is brought into gas-liquid contact with the absorbent slurry H1 and discharged as purified flue gas E5. Air F3 is blown as a number of fine air bubbles to oxidize sulfurous acid in the slurry to form gypsum, and a slurry H extracted from the absorption tower 61.
2 (gypsum slurry), such as a centrifuge for solid-liquid separation, and a filtrate H3 generated by the solid-liquid separation means 62.
And a filtrate pit 63 for storing the sorbent slurry, and an absorbent slurry pit 64 for producing the absorbent slurry H1. In addition,
A gypsum heating device such as a combustion furnace may be provided in which the solid content J2 (gypsum cake of gypsum dihydrate) separated by the solid-liquid separation means 62 is heated to about 120 ° C. to 150 ° C. to form gypsum hemihydrate.

Here, the absorption tower 61 has a slurry tank 65 at the bottom thereof to which the absorbent slurry H1 is supplied. Above this one slurry tank 65, in this case, the four tower main bodies 6 are provided.
6a, 66b, 66c and 66d are arranged side by side. Then, the slurry in the slurry tank 65 is sucked up by the circulation pump 67 and is injected upward in a liquid injection form from a spray pipe installed in each tower main body, so that the smoke and the smoke E4 are efficiently brought into gas-liquid contact. ing.

Note that, of the four tower bodies, the tower body 66
Reference numerals a and 66c denote so-called co-current gas-liquid contact towers, and tower main bodies 66b and 66d denote so-called counter-current gas-liquid contact towers. In addition, the flue gas E4 to be treated is, in this case, the tower body 66.
a from the top of the tower a, and then into the lower part of the tower main body 66b via the upper part of the slurry tank 65, and then through the connection duct 66e connecting the tower tops of the tower main body 66b and the tower main body 66c. It is introduced into the lower part of the tower body 66d via the upper part of the slurry tank 65, and finally discharged from the top of the tower body 66d.

Further, the outlet duct 69 of the exhaust gas E5 after the treatment is used.
, A mist eliminator 70 and an exhaust fan 71 are sequentially provided. The mist eliminator 70 is for removing entrained mist from the flue gas E5, and is supplied with washing water G4 such as industrial water as appropriate to wash the elements. The supplied cleaning water G4 and the removed liquid are finally introduced into the slurry tank 65 via the lower hopper of the mist eliminator 70, and become part of the slurry circulated in the absorption tower 61.

The exhaust fan 71 is for pumping the smoke exhaust against the pressure loss of the exhaust gas in the absorption tower 61 and the like, and for example, based on the detected value of the pressure in the buffer tank 51 described above. Capability is controlled. The exhaust gas E5 sent out by the exhaust fan 71 is released to the atmosphere from a chimney not shown.

The slurry tank 65 is provided with a fixed air sparger 72 for wiping the air F3 as fine bubbles and a stirrer 73 for stirring the entire slurry in the tank, and absorbs sulfurous acid gas and flows down from each tower body. The resulting slurry comes into efficient contact with the blown air, so that almost all of the absorbed sulfurous acid is oxidized, and furthermore, a neutralization reaction occurs with the calcium compound to produce high-purity gypsum.

In such a steady state, a slurry containing gypsum at a high concentration is supplied from the tank 65 to the pump 7.
4 and sent to the solid-liquid separator 62 as a slurry H2, where the solid-liquid separation is performed to collect a gypsum J2 as a solid content. The filtrate pit 63 generated by the solid-liquid separation
The filtrate H3 temporarily stored in the tank is appropriately sucked up by a pump 75, sent to the slurry tank 65 or the absorbent slurry pit 64, and finally returned to the slurry tank 65 in any case for circulating use. You.

In the absorbent slurry pit 64, a calcium compound J1 (for example, limestone) supplied from a silo (not shown) and a filtrate H3 in an amount corresponding thereto are mixed and stirred, and a predetermined concentration of the absorbent slurry H1 Is prepared.
The supply flow rate of the absorbent slurry H1 in the absorbent slurry pit 64 is controlled in accordance with, for example, the detected value of the amount of sulfurous acid gas in the flue gas E4 as the processing gas. Sent. In addition, in order to supplement the water evaporated in the absorption tower 61 and removed as steam in the flue gas, or the water contained in the gypsum J2 or the water discharged out of the system as adhering water, make-up water G3 such as industrial water is used.
Is supplied into the slurry tank 65 so as to maintain the liquid level in the slurry tank 65 within a certain range, for example.

Incidentally, in a general desulfurization apparatus attached to a thermal power generation facility or the like, in order to prevent impurities such as chlorine absorbed into the slurry together with the sulfurous acid gas from accumulating in the circulating slurry constituent liquid. For example, a part of the filtrate in the filtrate pit is discharged to the outside of the system, and after performing wastewater treatment, measures such as water discharge or reuse are taken. But in this example,
There is no need to perform such wastewater treatment. This is because, compared to the flue gas discharged from the thermal power plant, only a small amount of such impurities are present in the flue gas E4 to be treated in this example, so that the flue gas is discharged out of the system together with the plaster J2 and the like. This is because the accumulation of such impurities can be prevented by the liquid component.

Further, ammonia water M3 or M5 (shown in FIG. 5) described later may be used as a part or the whole of the above-mentioned makeup water G3. It has been found that when ammonia is injected in this way and the concentration of ammonium ions in the circulating slurry of the desulfurizer increases, the removal rate of sulfurous acid gas is significantly improved.

Next, the configuration and operation of the wastewater treatment section will be described with reference to FIG. The above-mentioned waste water B5 (shown in FIG. 3) discharged from the combustion cooling section is firstly supplied to the pH treatment tank 81.
Then, for example, an alkali K such as calcium hydroxide (Ca (OH) ₂ ) is added to adjust the pH to around neutral, and then the wastewater B6 is supplied to the circulation system of the evaporator 83 (primary concentrating means) by the pump 82. It is a configuration to be introduced.

The inside of the pH treatment tank 81 is almost at atmospheric pressure, and the wastewater B5 introduced therein is sent to the pH treatment tank 81 from the above-described gas cleaning section or desulfurization regeneration section. The state changes from a high pressure state to a normal pressure state. Therefore, the dissolved gas such as ammonia partially evaporates spontaneously, and this gas is diffused to the gas phase in the pH treatment tank 81. In this case, this gas is discharged by the fan 81a as off gas B7. As described above, the gas is mixed with the regeneration gas E2 introduced into the combustion furnace 52.

The evaporator 83 separates the wastewater B6 into a concentrated liquid L1 and a vapor M1 containing ammonia by evaporating the wastewater B6. In this case, the concentrated liquid L1 in the liquid pool at the bottom is sucked up by the circulation pump 84. After being heated by the heater 85 together with the newly introduced wastewater B6, it is jetted from above. The heater 85 is a heat exchanger that heats the circulating liquid to a temperature at which ammonia is diffused as a gas by the high-temperature steam D3 extracted from a part of a steam cycle in the power generation system, for example.

The concentrated liquid L1 extracted from the circulation system of the evaporator 83 passes through a tank 86 and a pump 87,
The gypsum is sent to a solid-liquid separator 88. In the solid-liquid separator 88, the gypsum J3 contained in the concentrated liquid L1 is selectively separated. The gypsum J3 is formed by combining sulfate ions supplied from the tank 10 in the gas cleaning section and present in the wastewater and calcium ions added in the pH treatment tank 81. The solid-liquid separator 88
Is, for example, a vacuum belt filter, and the sucked filtrate L2 is supplied to a filtrate tank 92 via a vacuum chamber 89 and a pump 90.

Further, the filtrate L2 in the filtrate tank 92 is sent to a roller-type secondary concentrating means 94 by a pump 93, dehydrated, and discharged as sludge J4. The sludge J4 contains a solid having a fine particle size that cannot be separated by the solid-liquid separator 88. The liquid separated by the secondary concentration means 94 is sent to, for example, the upstream side (evaporator 83 or the like) and reprocessed.

On the other hand, the vapor M1 containing ammonia drawn out from the top of the evaporator 83 is first cooled to the condensing temperature by the cooler 95, and then introduced into the condensate tank 96, where the condensed water containing ammonia (ammonia water) It is primarily stored as M2). The ammonia water M2 in the condensate tank 96 is extracted by the pump 97, sent to the distillation column 99 via the heat exchanger 98, and separated into the diluted ammonia water M3 and the concentrated ammonia water M5.

The distillation tower 99 is a so-called step tower such as a bubble bell tower, for example.
After being heated at 8, it is supplied to the upper part of the tower and flows down while contacting with the vapor M4 containing a high concentration of ammonia rising in the tower. The low-concentration diluted ammonia water M3 collected at the bottom of the distillation column 99 is supplied to the heater 1
At 00, the water is heated by the water vapor D4, so that ammonia, which is a dissolved gas component, is diffused to the gas side. Then, the vapor containing ammonia that has been diffused passes through a reflux section provided at the top of the distillation column 99, and becomes a vapor M5 containing ammonia at a higher concentration.
The concentrated ammonia is sent to the tank 101.

Here, the reflux section means that the steam M4 is
2 is produced by cooling by the
The concentrated ammonia water M5 stored in the steam M4 is supplied to the top of the distillation column 99 by the pump 104, whereby the steam (eg, steam) other than ammonia in the steam M4
Is liquefied more, the ammonia in the liquid is more diffused, and a higher concentration of aqueous ammonia M5 is obtained. The cooler 102 is a shell-and-tube heat exchanger that cools the steam M4 with a refrigerant G7 such as industrial water.

A part of the low-concentration diluted ammonia water M3 accumulated at the bottom of the distillation column 99 is
After being appropriately extracted by a line 106 branching from the discharge side of 05 and cooled by a heat exchanger 98 and a cooler 107, it is sent to a diluted ammonia tank 108.

The concentrated ammonia water M5 and the diluted ammonia water M3 stored in the concentrated ammonia tank 101 and the diluted ammonia tank 108 are subjected to denitration or sulfur trioxide neutralization on the downstream side of the combustion furnace 52 described above. Alternatively, it can be used for denitration treatment on the downstream side of a gas turbine for gasification gas power generation, or it can be used as a slurry constituent liquid of a sulfurous acid gas absorption tower 61. Since it is separated from water, it can be used properly according to the required ammonia concentration, which is convenient.

Next, a detailed configuration of the combustion furnace 52 in the combustion cooling section (FIG. 3) will be described with reference to FIG. As shown in FIG. 6, the combustion furnace 52 includes a furnace main body 120 and its accompanying devices and piping lines. The furnace body 120
A combustion chamber 121, and three heat exchange channels 123a, 123b, 123c, which are connected to the combustion chamber 121 in a parallel state and each of which is loaded with a ceramic heat storage body 122,
A burner 124 is provided in an upper part of the combustion chamber 121.

Here, the burner 124 is supplied with auxiliary fuel N (for example, LPG) and air F2 for burning the auxiliary fuel N at the time of starting, and burns the auxiliary fuel N in the combustion chamber 121 only at the time of starting. In addition, as this furnace main body 120,
Specifically, for example, a combustion furnace of an RTO regenerative deodorizer (model RI-3) manufactured by Chugai Furnace Co., Ltd. can be used.

Ancillary equipment and piping lines include a mixer 131 for mixing the regeneration gas E2 and the air F1, an introduction line 133 into which the processing gas P mixed by the mixer 131 is sent by a fan 132, and a purge gas Q. The purge line 134 to be sent and the exhaust gas E3 after combustion
An exhaust line 135 for exhausting the exhaust gas, a line 137 for extracting a part of the exhaust gas from the combustion chamber 121,
A mixer 136 for mixing a part of the flue gas separated from the combustion chamber 121 by the 37 into the flue gas E3, and a boiler for recovering heat from a part of the flue gas provided along the line 137 and extracted from the combustion chamber 121 A waste heat boiler 138 for heating the feed water R to generate steam S is provided.

The introduction line 133 and the purge line 1
34, the exhaust line 135, and each heat exchange passage 123a,
Between the open / close valves 141a to 123b and 123c.
141c, 142a to 142c, and 143a to 143c are provided, respectively.

The open / close valves 141a to 141a
c, 142a to 142c and 143a to 143c are controlled by a controller (not shown) according to a predetermined sequence or program, and operate so as to execute an operation described later. In this case, a part of the smoke E3 is sent into the purge line 134 by a fan (not shown), and a part of the smoke E3 is used as the purge gas Q.

Next, an example of the gas purification method of the present invention which is carried out in the above-described gas purification equipment will be described. First, in the cleaning section shown in FIG. 1, after the carbonyl sulfide in the product gas A1 is converted into hydrogen sulfide, the product gas A1
Is performed to remove impurities such as chlorine compounds and ammonia in the gas. Next, in the desulfurization tower 21 shown in FIG. 2, the product gas A3 is brought into gas-liquid contact with an absorbing solution of a sulfur compound (hydrogen sulfide) to absorb and remove the sulfur compound contained in the product gas (desulfurization step). Next, in the regeneration tower 22 shown in FIG. 2, heat is applied to the absorbing solution C1 that has absorbed the sulfur compound in the desulfurization step, and the regeneration gas E2 containing the sulfur compound is heated.
Is discharged (regeneration step).

Next, in the combustion furnace 52 shown in FIG. 3 and FIG. 6, the regeneration gas E2 generated in the regeneration step is efficiently burned by the operation described later to be converted into the flue gas E3 containing the sulfur dioxide gas ( Combustion process). Next, the cooling tower 5 shown in FIG.
At 3, cooling is performed by bringing the exhaust gas E3 into gas-liquid contact with the cooling liquid G1.

Further, in the gypsum recovery section shown in FIG. 4, the sulfur dioxide gas in the exhaust gas E4 after cooling is absorbed by the wet lime gypsum method to produce gypsum J2 as a by-product (gypsum recovery step). The wastewater discharged from the washing section, desulfurization regeneration section, etc.
5 and processed by the wastewater treatment shown in FIG. 5 to collect ammonia M3 and M5, and here also gypsum J3 is produced as a by-product.

In the above combustion step, the mixed gas (processing gas P) of the regeneration gas E2 and the air F1 is burned at 1000 ° C. or more in this case in the combustion chamber 121 (shown in FIG. 6) of the combustion furnace 52, so that the SO 2 The generation of ₃ is suppressed to an almost minimum amount, and most of the hydrogen sulfide (H ₂ S) in the regeneration gas E2 becomes sulfur dioxide (SO ₂ ) according to the above-mentioned reaction formula (1).

Hereinafter, a combustion furnace 52 for performing this combustion step will be described.
Will be described with reference to FIG. In FIG. 7,
Opening and closing valves 141a to 141c, 142a to 142c,
Of the valves 143a to 143c, the closed valve is illustrated by being painted black, and the valve that is open is illustrated by white.

In the combustion furnace 52, the operating states of the respective opening / closing valves are switched, so that (a), (b) and (b) of FIG.
The operation state shown in (c) is sequentially repeated at intervals of 60 to 70 seconds. Then, only during the time from the start-up until the temperature in the combustion chamber 121 reaches the set temperature of 1000 ° C. and stabilizes, a mixed gas of LPG and air is blown into the upper part of the combustion chamber 121 from the burner 124 and the flame 124 a is generated. It is formed. As a result, the following operation is realized.

That is, in the state shown in FIG. 7A, the heat exchange flow path 123a is an introduction path of the processing gas P formed by mixing the regeneration gas E2 and the air F1, and the processing gas P
Enters the heat exchange channel 123a from the introduction line 133 via the on-off valve 141a, and is introduced into the combustion chamber 121 after exchanging heat with the heat storage body 122 in the heat exchange channel 123a. In the transition period from the start to the steady state,
Since the heat storage body 122 in the heat exchange channel 123a has a low temperature,
The processing gas P thus introduced is not heated sufficiently to self-combust at a high temperature, but is reliably burned at 1000 ° C. or higher even when the concentration of hydrogen sulfide is low due to the flame 124 a from the burner 124. be able to.

The heat storage element 122 in the heat exchange channel 123a
Is heated by the exhaust gas of 1000 ° C. or more in the immediately preceding operation state shown in FIG. 7C, so that in the steady state, it is about 300 ° C. on the outside (far side from the combustion chamber) and about (Approx. Side).

For this reason, in the steady state, the heat storage element 122 having such a sufficiently high temperature makes the heat exchange passage 12
3a can be heated to about 750 ° C., and even when the concentration of hydrogen sulfide is low, even though the flame 124a from the burner 124 is stopped, the processing gas P is Can self-combust at temperatures above ℃. In the case of the steady state, FIG.
At the end of the operation state shown in (a) (immediately before switching to the next operation state), the heat storage body 122 in the heat exchange channel 123a is cooled by the processing gas P, and its temperature is 20
The temperature is about 0 ° C. and about 700 ° C. inside.

In the operation state shown in FIG. 7 (a), the heat exchange passage 123c serves as an introduction passage for the purge gas Q, and the heat exchange passage 123b serves as a discharge passage for the smoke E3. The gas produced by burning the gas together with the purge gas Q flowing from the heat exchange channel 123c via the on-off valve 142c and the on-off valve 14 via the heat exchange channel 123b.
The exhaust gas is exhausted from the exhaust line 3b and the exhaust line 135 as smoke E3.

Here, the heat exchange channel 123c is shown in FIG.
In FIG. 7A, the purge gas Q remains in the flow path because it functions as the introduction path of the processing gas P in the immediately preceding operation state. As a result, the remaining processing gas P is sent into the combustion chamber 121, and the contained hydrogen sulfide is mixed with the hydrogen sulfide in the processing gas P introduced from the heat exchange channel 123a by 1000.
Burns above ℃. The heat storage body 122 in the heat exchange flow path 123c has a cooling effect of the processing gas P in the immediately preceding operation state shown in FIG. ℃,
Further cooled slightly by contact with the purge gas Q,
At the end of the operation state shown in FIG.
It is about 80 ° C and about 680 ° C inside.

The heat storage element 122 in the heat exchange flow path 123b
Is the purge gas Q in the previous operation state shown in FIG.
In the steady state,
The temperature is about 180 ° C on the outside and about 680 ° C on the inside. For this reason, in the operation state shown in FIG. 7A, the combustion exhaust gas E3 passing through the heat exchange flow passage 123b by the heat storage body 122 having such a sufficiently low temperature is heated to 300 ° C.
It can be cooled to the extent. In the steady state, at the end of the operation state shown in FIG.
Conversely, the heat storage body 3b is heated by the exhaust gas E3, and its temperature is about 300 ° C. on the outside and about 800 ° C. on the inside.

Next, in the operation state shown in FIGS. 7B and 7C, the operation of each of the above heat exchange flow paths shown in FIG. It is switched to move to the flow path. First, in the operation state shown in FIG.
The heat exchange channel 123a on the left side is an introduction channel for the purge gas Q, and the central heat exchange channel 123b is the processing gas P (regeneration gas E2).
The same operation is performed with the heat exchange passage 123c on the right side and the exhaust passage for the smoke E3 being the exhaust passage for the smoke E3. And the next FIG.
In the operation state shown in (c), the left heat exchange channel 123a
Is the exhaust gas E3 discharge passage, the central heat exchange passage 123b is the introduction passage of the purge gas Q, and the right heat exchange passage 123c is the introduction passage of the processing gas P. The operation returns to the operation state shown in FIG.

Thus, in this case, the smoke E3 is brought into contact with any one of the three heat storage bodies 122 provided in the three heat storage bodies 122 to heat the specific heat storage body 122 and, at the same time, the other heat storage body 122 is burned. The operation of heating the processing gas P by bringing the processing gas P into contact with the previous processing gas P is continued while sequentially switching the heat storage elements 122. As a result, the heat recovered from the exhaust gas E3 using the heat storage elements 122 as a medium is used as the regeneration gas. By heating E2 and air F1 continuously, the combustion of hydrogen sulfide contained in the regeneration gas E2 at 1000 ° C. or higher can be continued in the combustion chamber 121.

More specifically, for example, a so-called heat-exchange combustion furnace having a simple heat exchanger for heating the processing gas by the heat of the combustion exhaust gas can be considered, but the heat exchange material (tube, tube sheet, element, etc.) is burned. Since it is cooled by the processing gas while being heated by the exhaust gas, it requires a high-grade material that can withstand a large difference between a high temperature and a low temperature from about 1000 ° C. to room temperature, and there is no practical material.

On the other hand, in a combustion furnace having such a heat storage type heat exchange function, heating and cooling (heat recovery) of the heat storage medium as the heat medium are performed independently, so that the heat storage medium as the heat medium is used. The temperature difference between the gas inlet (before heating) and the gas outlet (after heating) can be remarkably increased to about 700 ° C. in a temperature change range of only about 100 ° C. to 150 ° C. of the body. For this reason, thermal efficiency becomes remarkably high, and in the steady state, the auxiliary fuel N such as LPG and the air F2 therefor are not charged.
Combustion at a high temperature of 1000 ° C. or higher can be continuously realized.

In the steady state where the supply of the auxiliary fuel N is stopped, the combustion temperature in the combustion chamber 121 fluctuates due to fluctuations in the flow rate of the regeneration gas E2 if no operation is performed. In consideration of this, the combustion temperature is set so as to be at least 1000 ° C.
When the temperature greatly exceeds 0 ° C., for example, the waste heat boiler 13
By increasing the heat recovery amount by the flow rate control of the exhaust gas by that amount, the increase in the heating temperature of the heat storage body can be suppressed and kept at around 1000 ° C. In this way, the heat-resistant temperature (permissible temperature) of the material constituting the combustion chamber 121 can be minimized while maintaining the condition that the combustion temperature is 1000 ° C. or higher, thereby avoiding an increase in cost.

In this combustion step, the combustion temperature is 1
The temperature is maintained at 000 ° C. or higher according to the above-mentioned reaction formula (2).
Has the effect of suppressing the generation of SO ₃ by the reaction to a minimum amount. That is, according to the research by the inventors, for example, FIG.
As shown in the figure, the decrease in the amount of SO ₃ generated leveled off as the combustion temperature increased, and hardly changed at 1000 ° C. or higher. This tendency is the same regardless of changes in the concentration of hydrogen sulfide and the like. The data shown in FIG. 8 is based on the case where the concentration of hydrogen sulfide in the processing gas is 14.2% and the concentration of sulfur oxide (SOx) in the flue gas is 65000 ppm. The SO ₃ conversion (SO ₃ / SOx) is an extremely low value of about 2%.

As described above, according to the gas purifying equipment or the gas purifying method of this example, the sulfur compound and various impurities in the product gas A1 are removed, and the purified gas A is extremely clean.
5, and gypsum, which is industrially extremely useful, can be easily produced as a by-product.

In addition, the above-mentioned problems relating to the combustion step are eliminated, and the equipment cost and the operation cost are further significantly improved. That is, even if the concentration of hydrogen sulfide is low, combustion can be performed without supplying the auxiliary fuel N or the air F2 for burning the auxiliary fuel N at least in a steady state, and the auxiliary fuel N becomes unnecessary. In addition, the operating cost can be reduced by the amount that the power of the pump and the fan for feeding the auxiliary fuel N and the air F2 becomes unnecessary. Also,
Since there is no need to supply the auxiliary fuel N and the air F2, the flow rate of the flue gas E3 can be significantly reduced, the device capacity after the combustion process can be greatly reduced, and a fan or blower for gas supply after the combustion process can be used. And other operating costs can be significantly reduced.

In the combustion step of this embodiment, the combustion temperature is maintained at 1000 ° C. or higher, so that the amount of SO ₃ generated is suppressed to a minimum as described above, and the apparatus after the combustion step is used. It is not necessary to take any special measures such as improving the corrosion resistance of the equipment. In this regard, it is possible to reduce the equipment cost and also to reliably prevent the failure of the equipment members caused by SO ₃ .

Further, in the case of this embodiment, the waste heat boiler 138
The combustion temperature is constantly maintained at around 1000 ° C. even if the flow rate of the regenerating gas E2 fluctuates by adjusting the heat recovery amount of the combustion gas. This also has the effect of avoiding the occurrence of defects such as shortening the life of the device with high reliability.

The present invention is not limited to the above-described embodiment, and may have various aspects. For example, the number of heat exchange channels and heat storage elements in the combustion furnace of the present invention is not limited to three. For example, four or more heat exchange channels and heat storage elements are provided, and each role is performed by overlapping with a plurality of heat exchange channels and heat storage elements. You may make it.

[0094]

According to the gas purification method of the present invention, the sulfur compound in the produced gas is absorbed and removed by the absorbing solution in the desulfurization step, so that a clean purified gas can be obtained. Then, the regeneration gas containing the sulfur compound absorbed in the regeneration step is discharged, and this regeneration gas is converted into flue gas containing sulfur dioxide gas in the combustion step, and the sulfur dioxide gas in this plume is absorbed in the gypsum recovery step. Gypsum, which is industrially extremely useful, is produced as a by-product.

Further, in the combustion step, the exhaust gas after combustion is brought into contact with any specific one of the heat accumulators to heat the specific heat accumulator, and at the same time, the other heat accumulator is heated to the other heat accumulator before combustion. The operation of heating the regeneration gas by contacting the regeneration gas is sequentially performed by sequentially switching the heat storage body, so that the regeneration gas before combustion is heated by the heat recovered from the exhaust gas using the heat storage body as a medium.

Thus, the heating and cooling (heat recovery) of the heat storage medium as the heat medium are performed independently, so that the heat storage medium and the heat storage medium can be connected within a temperature variation range of only about 150 ° C. The temperature difference between the inlet and the outlet of the heat exchange gas can be significantly increased to about 700 ° C. For this reason, the thermal efficiency is remarkably increased, and in a steady state, high-temperature combustion can be continuously realized without supplying auxiliary fuel such as LPG and air therefor.

Therefore, the above-mentioned problems relating to the combustion step are eliminated, and the equipment cost and the operation cost are significantly improved. That is, even if the concentration of hydrogen sulfide is low, combustion can be performed in a steady state without introducing auxiliary fuel or air for burning the auxiliary fuel, and the purchase cost of the auxiliary fuel becomes unnecessary. In addition, the operating cost can be reduced by the amount that the power of the pump and the fan for feeding the auxiliary fuel and air is not required. In addition, since there is no need to supply auxiliary fuel and air for it, the flow rate of flue gas after combustion can be significantly reduced, the equipment capacity after the combustion process can be significantly reduced, and gas can be supplied after the combustion process. The operating costs of such fans and blowers can also be significantly reduced.

In the gas purification method according to the second aspect,
Since the combustion temperature is kept at 1000 ° C. or higher, the amount of SO ₃ generated is suppressed to a minimum as described above, and special measures such as improving the corrosion resistance of the equipment after the combustion step are taken. This eliminates the necessity, and in this regard, it is possible to reduce the equipment cost, and it is also possible to reliably prevent problems such as corrosion of device members due to SO ₃ .

Next, in the gas purifying facility according to the third aspect,
In the desulfurization tower, sulfur compounds in the product gas are absorbed and removed by the absorbing solution, and a clean purified gas is obtained. And
The regeneration gas containing the sulfur compounds absorbed in the regeneration tower is discharged, and the regeneration gas is converted into flue gas containing sulfur dioxide gas by a regenerative heat exchange combustion furnace, and the sulfur dioxide gas in the flue gas is absorbed in a desulfurization unit. As a result, gypsum which is extremely useful industrially is produced as a by-product.

Here, the regenerative heat exchange combustion furnace has a plurality of heat exchange passages which are connected in parallel to the combustion chamber and each of which is provided with a heat storage body, and these heat exchange passages are used for regeneration of the combustion chamber. A configuration is adopted in which the gas is sequentially switched as a gas introduction path or a smoke exhaust path after combustion.

Therefore, the exhaust gas comes into contact with the heat storage material in any one of the heat exchange passages to heat the specific heat storage material, and at the same time, the heat storage material in the other heat exchange flow passage is regenerated before combustion. The operation in which the regeneration gas is heated by contact with the gas is continuously executed by sequentially switching the heat exchange flow path and the heat storage, and the heat recovered from the exhaust gas after combustion using the heat storage as a medium. Heats the regenerated gas before combustion.

As a result, heating and cooling (heat recovery) of the heat storage medium as the heat medium are performed independently, so that the heat storage medium and the heat storage medium can be separated within a temperature variation range of only about 150 ° C. The temperature difference between the inlet and the outlet of the heat exchange gas can be significantly increased to about 700 ° C. For this reason, the thermal efficiency is remarkably increased, and in a steady state, high-temperature combustion can be continuously realized without supplying auxiliary fuel such as LPG and air therefor. Therefore, the above-mentioned problem relating to the combustion furnace is solved, and the equipment cost and the operation cost are significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a gas cleaning unit of a gas purification facility as an example of the present invention.

FIG. 2 is a diagram showing a configuration of a desulfurization regeneration unit in the same equipment.

FIG. 3 is a diagram showing a configuration of a combustion cooling unit in the facility.

FIG. 4 is a diagram showing a configuration of a gypsum collecting unit in the same equipment.

FIG. 5 is a diagram showing a configuration of a wastewater treatment section in the facility.

FIG. 6 is a diagram showing a detailed configuration of a combustion furnace of the facility.

FIG. 7 is a view showing the operation of the combustion furnace of the facility.

FIG. 8 is a diagram showing an example of data indicating a correlation between the concentration of sulfurous acid gas generated by the combustion of hydrogen sulfide and the combustion temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Desulfurization tower 22 Regeneration tower 52 Combustion furnace (storage type heat exchange combustion furnace) 121 Combustion chamber 122 Heat storage body 123a, 123b, 123c Heat exchange flow path A1-A5 Product gas C1 Absorbent (for absorption of sulfur compounds) E1, E2 regeneration Gas E3, E4 Flue gas H1 Absorbent slurry (for absorbing sulfurous acid gas)

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shintaro Honjo 4-6-122 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Inside the Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd.

Claims (3)

[Claims] 1. A gas refining method for purifying a product gas obtained by gasification of coal or petroleum, wherein said product gas is brought into gas-liquid contact with an absorbing solution of a sulfur compound to thereby remove sulfur contained in said product gas. A desulfurization step of absorbing and removing the compound, a regeneration step of applying heat to the absorbing solution having absorbed the sulfur compound in the desulfurization step to discharge a regeneration gas containing the sulfur compound, and burning the regeneration gas generated in the regeneration step A combustion step of converting the gas into flue gas containing sulfurous acid gas, and a gypsum recovery step of absorbing the sulfurous acid gas in the flue gas generated in the combustion step by a wet lime gypsum method to produce gypsum. Provide a plurality of heat storage for the combustion chamber to perform, at the same time heating the specific heat storage by contacting the exhaust gas to any one of these heat storage,
The operation of heating the regenerating gas by contacting the regenerating gas before combustion with another regenerator is sequentially performed by switching the regenerator sequentially, thereby recovering the regenerator as a medium from the flue gas. 2. The gas purification method according to claim 1, wherein the combustion step is performed while heating the regeneration gas with heat. 2. The gas purification method according to claim 1, wherein the combustion temperature of the regeneration gas in the combustion step is set to 1000 ° C. or higher. 3. A gas refining facility for purifying a product gas obtained by gasification of coal or petroleum, wherein said product gas is brought into gas-liquid contact with a sulfur compound absorbing solution to contain sulfur contained in said product gas. A desulfurization tower that absorbs and removes the compound, a regeneration tower that applies heat to the absorbing solution that has absorbed the sulfur compound in the desulfurization tower to discharge a regeneration gas containing the sulfur compound, and burns the regeneration gas generated in the regeneration tower. A regenerative heat exchange combustion furnace that converts to flue gas containing sulfurous acid gas, and a desulfurization device that absorbs sulfurous acid gas in the flue gas generated in the regenerative heat exchange combustion furnace by wet lime gypsum to produce gypsum as a by-product The regenerative heat exchange combustion furnace comprises: a combustion chamber; and a plurality of heat exchange flow paths that are connected to the combustion chamber in a parallel state and are each loaded with a heat storage body. The regeneration gas for a combustion chamber Introducing path or sequentially switched are configured and the possible gas purification equipment, wherein the discharge path of the flue gas.